Hashtable to Dictionary

Question

I am trying to convert a hashtable to disctionary and found a a question here: convert HashTable to Dictionary in C#

public static Dictionary<K,V> HashtableToDictionary<K,V> (Hashtable table)
{
    return table
        .Cast<DictionaryEntry> ()
        .ToDictionary (kvp => (K)kvp.Key, kvp => (V)kvp.Value);
}

When I try to use it, there is an error in table.Cast; intellisense does not show "Cast" as a valid method.

Answer 1

Enumerable.Cast doesn't exist in .NET 2, nor does most of the LINQ related methods (such as ToDictionary).

You'll need to do this manually via looping:

public static Dictionary<K,V> HashtableToDictionary<K,V> (Hashtable table)
{
    Dictionary<K,V> dict = new Dictionary<K,V>();
    foreach(DictionaryEntry kvp in table)
        dict.Add((K)kvp.Key, (V)kvp.Value);
    return dict;
}

Answer 2

Enumerable.Cast is in the System.Linq namespace. Unfortunately, LINQ is not part of .NET 2. You will have to upgrade to at least version 3.5.